This invention relates to a control method for stopping a DC motor, particularly a DC servomotor, at a predetermined position.
DC servomotors are commonly employed to drive a movable element, and are particularly suited for driving the embroidery frame of an automatic embroidery machine. In such machines it is often necessary to stop the movable element at a predetermined position by suitable control of the DC servomotor, wherein the output shaft of the servo motor is brought to a halt at a prescribed orientation or stopping position. A problem encountered in effecting such control is that it is difficult to constantly hold gain of the control system at an optimum value when there are variations in load torque. Since an improper control system gain does not permit a consistent control accuracy to be attained, the output shaft of the servomotor cannot always be stopped at the point desired. It is conventional practice in the art to achieve the optimum gain by a regulation method, but a less troublesome and more precise method of control is desired.